Photographic registration and compositing method for preparing resists for etching gravure cylinders



CAlNE INVENTOR.

ETGHING GRAVURE CYLINDERS Filed June 20, 1961 Feb. 1, 1966 PHOTOGRAPHICREGISTRATION AND COMPOSITING RESISTS FOR United. States Patent M3,232,760 PHGTOGRAPHIC REGISTRATION AND CGMPOSIT- 'ING METHOD FORPREPARING RESISTS FUR ETCH'ING GRAVURE. '(IYLINDERS Rolland H. Cains,Park Ridge, llll., assignor to R. 'R.

Donnelley & Sons Company, a corporation of Delaware Filed June 20, 1961,Ser. No. 118,409 4 Claims. (Cl. 96-43) This invention relates to amethod of and apparatus for preparing resists suitable for use inetching gravure cylinders.

conventionally, such resists are prepared from carbon tissue. This termdesignates paper having a gelatin coating. Before use this gelatincoating is rendered light sensitive by treatment With a bichromatesolution. Thus sensitized carbon tissue is characterized by low lightsensitivity, as compared with conventional silver halidegelatinemulsions used in ordinary photographic films. For instance, at a lightintensity of 20 foot candles, similar results are obtained by exposingsensitized carbon tissue for 5 hours; a fast silver halide emulsion for40 seconds; and a slow silver halide emulsion for 2 or 3 minutes. Inother terms, equivalent exposure is obtained by exposing carbon tissueto an amount of light energy on the order of 350,000 foot candleseconds; a fast silver halide emulsion to 800 foot candle seconds; and aslow silver halide emulsion to about 2,000 to 3,000 foot candle seconds.The range of speeds extending from fast to slow as applied to silverhalide-gelatin emulsions in this paragraph is hereinafter referred to ascamera speed.

When sensitized carbon tissue is used to prepare a gravure resist,conventionalor standard practice involves first making a photographicnegative from the original art copy, then preparing a positive from thisnegative, and finally exposing the carbon tissue to contact printingwith this positive under intense illumination. One reason, among others,why this procedure is conventional is the fact that any enlargement orreduction in size of the original copy must be taken care of when thephotographic negative or positive is prepared, since the conventionalcontact printing exposure of the carbon tissue does not permit anyenlargement or reduction in size.

The present invention is particularly concerned with the reproduction ofcopy of the type furnished for the gravure printing of catalogues.Catalogue pages contain both text or type matter and a number ofseparate illustrations, the various parts of all this matter beingpositioned properly (in register) with respect to each other on eachprinted page. The copy, as furnished to the printer, is made up of twoseparate parts: text or type matter and art work. The text or typematter is prepared for use in making a resist in the form of one or morepositive transparencies. The term transparency signifies a transparentsheet of cellulose acetate or the like carrying the text matter asopaque type applied thereto by any suitable conventional method; forinstance, by proofing from a type form or by photocomposition. The typecopy is, as a rule, of the exact size to be reproduced on the printedpage. The art copy is made up of one, or usually more than one, piece ofart work, each, as a rule, of a size requiring the same enlargement orreduction in size before the resist is made. Specifically, the art copyusually requires enlargement or reduction in order at least to effectproper proportioning with respect to the type matter. For instance, theart copy may require a size reduction from 1%. to 1 While the type copyis furnished in the exact size to be reproduced. For preparation of aresist according to the present invention, this art work is mounted onsuitable sheet material as described in detail hereinbeloW.

printed in its original size.

3,232,760 Patented Feb. 1., 1966 The present invention provides a methodand a photographic device for use in preparing grav-ure resists from theoriginal copy described in the preceding paragraph. The invention may beused in the preparation of a resist directly from the copy or in thepreparation of the intermediate negative or positive produced in theconventional method of making gravure resists, as mentioned hereinabove.

According to the present invention, the separate pieces of art work aremounted on an-atJleast slightly translucent sheet, in the relativepositions in which they are to appear on the printed page. This sheetmust be white, and should transmit at least 5 percent of white light.For this purpose, so called artists board may be used. That side of thesheet carrying the art work is hereinafter referred to as the frontside, the other side as the rear side. The rear side of the sheet isopaqued exclusively behind the art copy, so that no light can peneratethe art "copy while at least a small amount of lightcan still peneratethe slightly translucent sheet outside the art copy. Such opaquing canbe carried out by any suitable conventional method, as by manualapplication of an opaque ink, by application of opaque tape, or byapplication of an opaque mask. If desired, the art work itself can beopaqued on its rear side before it is mounted on the translucent sheet.

The above described translucent sheet carrying the art work and thetransparency carrying the type matter are both placed in thephotographic printing device of the present invention, for effectingsimultaneous or concurrent printing exposure thereof on a lightsensitive film.

In the photographic print-ing device of the present-invention, the sheetcarrying the art copy is illuminated on both sides. The ad copy isprojection printed-on the light sensitive film exclusively by reflectedlight. Note that the opaquing of the rear side of the art work preventspenetration of the art work by the light illuminating the rear side ofthe translucent sheet. However, this light can penetrate the sheet inquestion outside the art copy, so that these outside sheet areas,*unde'rthe influence of both reflected and transmitted light, will printas though they were brilliantly white, and, therefore, also more whitethan any part of the art work. In this manner, the background around theart Work is dropped out and reproduces as a uniformly white surfacesurpassing the whiteness of any part of the art work. It should beremembered, in this connection, that a photographic negative is obtainedin the printing step described in this paragraph, and that thisnegative, after development and when used as a resist, will protect thegravure cylinder against etching proportionally to the amount ofexposure locally received by the light sensitive film. Hence, white copyareas, which permit intense exposure, yield lightly etched cylinderareas, and these lightly etched cylinder areas transmit only smallamounts of ink to the paper being printed. The same is true when thenegative is not used directly as a resist but is reproducedphotographically as a positive which is then used'to make a resist.

At the same time as the art copy is projection printed on the lightsensitive film, with its background dropped out, the type matter iscontact printed on the film. For this purpose, and before the film isexposed, the transparency carrying the type matter in the form of opaquecharacters is placed on the film in proper relative position or registerwith respect to the art copy, sothat the type matter will be reproducedin the desired position on the printed page.

It will be noted that the type matterv is printed on the film in itsoriginal size. The art copy, on the other hand, may be enlarged, orreduced, as desired, as it is projection printed. In exceptional cases,the art work may be Both type and art copy are printed in a singleexposure, which also serves to drop out the art background.

The photographic printing device of the invention is illustrateddiagrammatically in the accompanying drawings, in which:

FIG. 1 is a plan view of the device;

FIG. 2 is a section taken substantially as indicated along the line 22of FIG. 1; and

FIG. 3 is an and elevation as indicated by th line 33 of FIG. 2, withpart of the enclosure broken away.

As shown in the drawing, the device in question includes a box-likeenclosure indicated generally at and having vertical side walls 12 and14, and vertical end walls 16 and 18 all connected to a horizontalbottom 20. The end wall 16 is continued upwardly by a glass wall 22which slopes inwardly at about 45, while the other end wall18 iscontinued upwardly by a glass wall 24 also inclined inwardly at about45. Note that the glass wall 24 is larger in area than the glass wall22. The top of the device is closed by offset horizontal walls 26 and 28connected by a vertical wall 30. The box-like structure 10 defined bythe above described elements is light tight except for the glass walls22 and 24.

Within the enclosure 10 suitable light sources such as sets 32 and 34 offluorescent tubes are provided for directly and uniformly illuminatingthe glass wall 24 and also for illuminating the glass wall 22 by meansdescribed as follows. A tubular shield 36, of rectangular crosssectional shape, has one end of the same size as the glass wall 22attached to the edges of the latter and extends inwardly into the box 10in a direction normal to the glass wall 22. As shown, the shield taperstowards the inner, unattached end, and there supports a lens system 38and a reflecting reversing prism 40.

The device of the drawings further includes a movable cover 42 for theglass wall 22 supported by a bracket 44, and a movable cover 46 for theglass wall 24, flanged as indicated at 48 and supported by a bracket 50.A source of light, such as a set 52 of fluorescent light bulbs, issupported from the flanges 48 Within the enclosure defined by theseflanges, the cover 46 and the glass wall 24. A transparent plate 54overlies the glass wall 24 beneath th cover 46, for urging thereagainsta translucent sheet 56 carrying the art work (as described hereinabove)with its front side contacting the glass wall 24. A transparencycarrying the type matter is indicated in the drawings by the referencenumeral 58, and a light sensitive film by the reference numeral 60; andthese are supported, as shown, with the transparency contacting theglass wall 22, the film contacting the transparency, and both held downby the cover 42.

The optical system of the device of the drawing is so arranged as toproject onto the film 60 and unreversed image of the art Work on thesheet 56, at any desired reduction in size, or, if necessary, anydesired enlargement, or, exceptionally, without any change in size. Forthis purpose, the optical system may include any conventional lenssystem 38 and reversing reflecting prism 40. r

In the use of the apparatus, the sheet 56 is first fixed on theglasswall 24 as by taping it, the transparency 58 is similarly disposedon the glass wall 22, and a translucent sheet is placed overtransparency 58, in place of the sensitive film 60. The device may thenbe used as a viewer, by inspecting the translucent sheet to see therelative positions of the sheet 56 and the. transparency 58', since animage of the art work on the sheet 56 is projected through the glasswall 22 onto the translucent sheet, andat the sam time, the transparency58 is seen through the sheet. At this time, the relative positions ofthe sheet 56 and of the transparency 58 may be adjusted for properregistration.- l 1 When register has been obtained, the translucentsheet is removed, the film 60 issuperimposed over the transparency 58,and the cover 42 is placed on top of the film to hold them bothfirmlyagainst the glass wall 22. The

cover 42 may be opaque, to exclude all external light from the film Onthe'other hand, it is often preferred to dispose the left portion of theenclosure 10 within a darkroom, which permits the use of a translucentcover 42 and eliminates the need for a separate translucent sheet Whenthe images of the sheet 56' and the transparency 58 are being adjustedfor registration.

The cover 42 and plate 54 may be replaced, if desired, with otherconventional devices for holding the sheets or films firmly against theglass walls 22 and 24; for instance, conventional vacuum frames, whichmay be transparent or opaque, as required.

When the transparency 58 and the sheet 56 have been disposed in properregistration, the film 60 has been placed over the transparency, thecover 42, and transparent plate 54 have been disposed over the film 60and the sheet 56, respectively, the cover 46 carrying lamps 52 is closedand the film 60 is exposed by using only the light from the lightsources 32, 34 and 52. This exposure is carried out under suchconditions as are appropriate in view of the light sources, film andcopy being used, as will be apparent to anyone skilled in the art.

When some type matter takes the form of reverse type (white type on ablack or gray background), supplied in the form of a positivetransparency, the transparency 58 may be replaced by the transparencycarrying the reverse type, and a second exposure of the film 60 may thenbe carried out exactly as described hereinabove, but vwith sheet 56,removed and a translucent sheet substituted therefor.

For preparing a resist directly from the copy; i.e., without preparingan intermediate negative and positive, as is done conventionally, thelight sensitive film mentioned hereinabove may be sensitized carbontissue or, preferably, a silver halide-gelatin emulsion of camera speedsupported by a strippable backing film or layer. This emulsion may bepanchromatic, orthochromatic, or blue sensitive. Examples of such filmsare disclosed in US. Patent Nos. 2,628,903, 2,638,417, 2,650,877,2,650,878, 2,907,567 and 2,976,147. In such films, the exposed emulsionareas are selectively hardened and after develop ment from the desiredresist.

For preparing a finished resist directly from copy, other and furthersteps are required besides the exposure previously described. Forinstance, a screening exposure of the film must be made before or afterexposure of the present invention. In the case of exposed carbon tissue,the further treatments and steps are conventional and so well known inthe art that no description thereof is needed. The further treatment ofa light sensitive film containing a silver halide-gelatin emulsionincludes developing, fixing, washing, selective hardening, drying,laying down on the cylinder, and removal of the strippable supportbefore etching is done. All these steps are carried out in conventionalfashion; for instance, as disclosed in the above identified US. patents.Further, as may be desired, the film (either carbon tissue or a silverhalide-gelatin emulsion) may be subjected to supplemental exposures, asfor compressing the density range of the finished resist, or forinsuring equal density of type matter and heavy portions of the artcopy, and the like. Such supplemental exposures are within the skill ofthe art.

The present invention may also be used in the preparation of. the abovenoted negative and positive reproductions conventionally made (on alight sensitive silver halide-gelatin emulsion) in the course of makinga resist. Specifically, in making such a negative reproduction, it neednot be made of the exact size of the finished resist, since it may beenlarged or reduced when the positive reproduction is made. In thisspecific case, the present invention may be used for establishing propersize proportions as between type matter and art copy, withoutnecessarily having the type matter (on the positive reproduction) of theexact size desired in the resist. it is possible, therefore, in such acase, to have the original type matter of a size different from thatdesired in the finished resist.

The present invention may also be applied to the preparation of anautopositive photographic reproduction of the original copy, forsubsequent use in the preparation of a resist.

Many details may be varied without departing from the principles of thisinvention, which are set forth in the appended claims. While thisinvention has been disclosed and described as specifically applied tothe preparation of gravure resists, it should be understood that it maybe used whenever it is desired to drop out background to art copycombined with type matter as described hereinabove.

I claim:

1. In a method of preparing a gravure resist or the like, the stepscomprising providing first copy in the form of a transparency, providingopaque second copy mounted on a slightly translucent sheet whichprovides a back ground for the second copy, and concurrently exposing alight sensitive film to contact printing through said transparency andto projection printing both with light reflected from said second copyand with light transmitted through said translucent sheet, whereby thebackground of said second copy is dropped out as said first copy andsecond copy are reproduced on said film.

2. In a method of preparing a gravure resist or the like the stepscomprising providing a light sensitive film, providing type copy in theform of a transparency, providing art copy in the form of separatepieces of opaque art work mounted on the front side of a translucentsheet, disposing said film in a photographic printing device, disposingsaid transparency in said printing device in front of said film forcontact printing on said film of said type matter, disposing said sheetin said printing device spaced from said film for projection printing onsaid film of said art Work, and concurrently illuminating saidtransparency and both front and rear sides of said sheet whileprojecting on said film an image of said art work, whereby said art workis printed on said film with its background dropped out.

3. A method of preparing a gravure resist directly from copy, saidmethod comprising providing a film having a front layer of lightsensitive resist-forming silver halidegelatin emulsion of camera speedand also having a strippable supporting rear layer, providing type copyin the form of a positive transparency to be reproduced in its originalsize, providing art copy in the form of separate pieces of art Work,mounting said pieces of art work on the front side of a translucentsheet, opaquing the rear sides of said pieces of art work, disposingsaid transparency in contact with the front side of said film, disposingsaid sheet in spaced relationship to said transparency and in a positionsuch that an image of said art work may be projected onto said film inregistration with the type copy of said transparency, and concurrentlymaking a photographic printing exposure of said film through saidtransparency and a photographic projection printing exposure of saidfilm with light reflected from said art work and projected through saidtransparency onto said film, said translucent sheet being simultaneouslyilluminated from the rear, whereby the background of said art work isdropped out.

4. The method of claim 1 in which the first copy is type copy and thesecond copy is art copy.

References Cited by the Examiner UNITED STATES PATENTS 1,053,987 2/ 1913Sontag 9642 1,572,899 2/ 1926 Mastrukotf. 1,755,129 4/1930 Pomeroy 96421,808,743 6/ 1931 Barkolew. 1,841,274 l/1932 Ballard 96-43 1,863,8266/1932 Briel 9642 X 2,236,458 3/ 1941 Verriour 9643 2,488,177 11/1949Dufour. 2,580,422 1/ 1952 Gunn. 2,609,294 9/1952 Prentice 9642 2,628,9032/1953 Kott 9638 2,638,417 5/1953 White et al 9683 2,641,963 6/1953Carter. 2,650,877 9/1953 Boyer 9638 2,650,878 9/1953 Boyer et al 96382,740,712 4/ 1956 Pohl 9642 2,907,657 10/1959 Kott 9638 2,920,527 1/1960 Claupeau. 2,976,147 3/ 1961 Alles 9683 FOREIGN PATENTS 590,5593/1925 France.

NORMAN G. TORCHIN, Primary Examiner. PH L IP E- MA GA Exam

1. IN A METHOD OF PREPARING A GRAVURE RESIST OR THE LIKE, THE STEPSCOMPRISING PROVIDING FIRST COPY IN THE FORM OF A TRANSPARENCY, PROVIDINGOPAQUE SECOND COPY MOUNTED ON SLIGHTLY TRANSLUCENT SHEET WHICH PROVIDESA BACKGROUND FOR THE SECOND COPY, AND CONCURRENTLY EXPOSING A LIGHTSENSITIVE FILM TO CONTACT PRINTING THROUGH SAID TRANSPARENCY AND TOPROJECTION PRINTING BOTH WITH LIGHT REFLECTED FROM SAID SECOND COPY ANDWITH LIGHT TRANSMITTED THROUGH SAID TRANSLUCENT SHEET, WHEREBY THEBACKGROUND OF SAID SECOND COPY IS DROPPED OUT AS SAID FIRST COPY ANDSECOND COPY ARE REPRODUCED ON SAID FILM.